1. Field of the Invention
This invention relates to the field of integrated circuits. More particularly, this invention relates to the detection of operational errors within the processing stages of an integrated circuit and recovery from such errors.
2. Description of the Prior Art
It is known to provide integrated circuits formed of serially connected processing stages, for example a pipelined circuit. Each processing stage comprises processing logic and a latch for storing an output value from one stage which is subsequently supplied as input to the succeeding processing stage. The time taken for the processing logic to complete its processing operation determines the speed at which the integrated circuit may operate. The fastest rate at which the processing logic can operate is constrained by the slowest of the processing logic stages. In order to process data as rapidly as possible, the processing stages of the circuit will be driven at as rapid a rate as possible until the slowest of the processing stages is unable to keep pace. However, in situations where the power consumption of the integrated circuit is more important that increasing the processing rate, the operating voltage of the integrated circuit will be reduced so as to reduce power consumption to the point at which the slowest processing stage is no longer able to keep pace. Both the situation where the voltage level is reduced to the point at which the slowest processing stage can no longer keep pace and the situation where the operating frequency is increased to the point at which the slowest processing stage can no longer perform its processing will give rise to the occurrence of processing errors that will adversely effect the forward-progress of the computation.
It is known to avoid the occurrence of such processing errors by setting an integrated circuit to operate at a voltage level which is sufficiently above a minimum voltage level and at a processing frequency that is sufficiently less than the maximum desirable processing frequency taking into account properties of the integrated circuits including manufacturing variation between different integrated circuits within a batch, operating environment conditions, such as typical temperature ranges, data dependencies of signals being processed and the like. This conventional approach is cautious in restricting the maximum operating frequency and the minimum operating voltage to take account of the worst case situations.
There is a need for a technique for reducing the operating margins of integrated circuits while also reducing the overhead of error detection and error correction circuits and operation.